Whenever am making a south indian dish, be it idli, dosa, uttapam, or pongal, I prefer to make chutneys that goes with it, else somehow I find justice is not done to the food. Two most common chutneys that I make are 1) Coconut Chutney and 2) Onion Tomato Chutney. Both of these are easy to make (Who does not like easy recipes?), as well does not take huge effort and ingredients for this chutney are available in generally in kitchen cupboard.
You can make this chutney and can keep it refrigerated for a week or so. In my case, I end up dishing it in couple of days as I could barely resist myself eating it and numerous times I just eat this chutney on its own, such delicious I find it 😀
The key ingredients are tomatoes, onion and bengal gram (Chana). In old days (and still in few households) this chutney is made using traditional tools (stones) for grinding. Unfortunately, I do not have that here in UK, and I have used mixer grinder to make this. I am assuming these days most households have a mixer grinder or food processor, and that helps in preparing this chutney in few minutes.
The proportions of onion, tomato and bengal gram is something that I use to get the kind of taste and consistency of chutney, however, you can vary the quantity to suit your own tastebuds.
I will also request you to checkout my recipe for Green Chutney (Mint Coriander Chutney), which is north indian style and goes well with numerous food items.